Intermittent reciprocatory feeding apparatus



J. HALLER 2,622,874

INTERMITTENT RECIPROCATORY FEEDING APPARATUS 2 SHEETS-SHEET 1 Dec. 23,1952 Filed Aug. 21, 1948 mQ @9 S QQ Dec. 23, 1952 J. HALLER INTERMITTENTRECIPRCCATORY FEEDING APPARATUS 2 SHEETS--Sl-IEET 2 Filed Aug. 21, 1943Illllllx Patented Dec. 23, 1952 UNITED STATES PATENT OFFICE INTERMITTENTRECIPROCATORY FEEDING APPARATUS This invention relates to materialfeeding arrangements and, in particular to arrangements for feedingsheet material or coil stock intermittently to processing machinesutilizing such material, such as punch presses, or stamping or shearinmachines.

One object of this invention is to provide an intermittent feedinarrangement for sheet or coil material wherein the material is engagedby clamps actuated by hydraulic fluid, the flow of which is controlledby a hydraulic device attached to the machine, thereby bringing about analmost instantaneous response of the feeding mechanism to the motion ofthe machine.

Another object is to provide an intermittent feeding arrangement of theforegoing character for sheet or coil material wherein the machine beingserved is provided with a pair of hydraulically operated clampingdevices, one of which is station-arily mounted on the machine bed andthe other mounted on a reciprocable slide, the clamping devices beingalternately engaged so that the sheet material is advancedintermittently, the clamping devices being operated by hydraulic fluid,the flow of which is controlled in response to the action of a hydraulicpump attached to a moving part of the machine being served.

Another object is to provide an intermittent feeding arrangement of theforegoin character for sheet or coil material wherein the pressure fluidfor intermittently actuating the material clamping devices is suppliedfrom a hydraulic pump or other suitable source, the flow of pressurefluid being controlled by a valve which in turn is actuated by aservo-motor hydraulically connected to a hydraulic piston and cylinderdevice connected to a moving part of the machine being served, asequence valve being preferably included in the circuit to deferoperation of the hydraulic feeding motor until a predetermined pressurehas been built up in the clamping circuit.

In the drawings:

Figure 1 is a side elevation, partly in section, of a feedingarrangement for sheet material, attached to a punch press, accordin to apreferred form of the invention;

Figure 2 is a top planview of the feeding arrangement shown in Figure 1;

Figure 3 is a vertical cross-section taken along the line 3-3 in Figure1, showing the details of one of the hydraulic clamps;

Figure 4 is a diagrammatic central longitudinal section through thefour-way valve shown 5 Claims. (Cl. 271-25) '2 in side elevation at thelower right-hand of Figure 1;

Figure 5 is a fragmentary Side elevation of a control device slightlymodified from that shown in the upper left-hand corner of Figure 1 so asto operate the feeding mechanism on the downstroke of the machine,rather than on the upstroke as in Figure 1; and

Figure 6 is a side elevation, partly in longitudinal section, of asequence valve preferably used in the hydraulic circuit shown in Figures1 and 2.

Referring to the drawingsin detail, Figure v1 shows a sheet metalworking machine, generally designated Ill, such as a punching orstamping press, adapted to be served by an automatic feedingarrangement, generally designated ll, according to a preferred form ofthe present invention. The machine It) is conventional andthe detailsform no part of the present invention. As shown diagrammatically inFigure 1, the ma.- chine l 6 consists of a bed l2 having vertical guidemembers l3 secured thereto by means not shown and serving toreciprocably guide a platen [4. The machine in is provided with a baseor bed [5 to which is bolted a die .unit It having a pair of diecavities l1 and I8 cooperable with punches l9 and 20 of a punch unit 21secured to the lower end of the platen I4.

Bolted or otherwise secured to the platen I 4 is the horizontal arm 22of an L-shaped bracket 23 to the vertical arm 24 of which a cam plate 25is adjustably secured. For this purpose the .cam plate 25 is providedwith a pair of vertically? spaced arms 26 bored to receive the bracketarm 24 and having set screws 21 threaded into the ends thereof to engageand clamp thecam plate 25 in any position of adjustment vertically alongthe bracket 23. The cam plate 25. is provided with a zig-zag cam groove28 having an upper horizontal portion 29 connected by an inclinedportion 30 to a lower horizontal portion 3|. v,

Mounted in the cam groove 28 is a roller or cam follower 32 which inturn rotates upon an axle 33 mounted on the end of a piston rod. 34 of amotive device generally designated 35. The latter is connected to theguide member l3 by a bracket 36 bolted thereto, and consists of a casing31 having a reservoir 38 in the upper portion thereof closed by a coverplate 39 and connected by a passageway 4!} to a valve chamber 5!containing a check valve or relief valve 42. The latter is urgeddownwardly into a seat 43 by a coil corner spring 441, the upper end ofwhich engages a plug 45 threaded into the upper end of the valve chamthecylinder 52.

her 4|. The valve chamber 4| below the valve seat 43 is connected by apassageway 45 to the right-hand end of a cylinder bore 41 having anoutlet port 48 in one end thereof. Reciprocably mounted in the cylinderbore 41 is a piston head 49 which, in turn, is mounted upon the pistonrod 34. The reservoir 39 is directly connected to the left-hand end ofthe cylinder bore 4'! by a passageway 50; 'I'heireservoir 33 contains asuitable hydraulic liquid, such as oil.

Extending downwardly from the port 48 to a port 5| in the cylinder 52 ofa servomotor 53 is a fluid supply pipe 54 which servesto conveyhydraulic fluid to and from the motive device 35. The servomotor 53 hasa cylinder bore 55 which is considerably less in volume. than. thecylinder bore 47 of the motive device 35, so that a crowding effect isobtained. By this crowding effect, the excess fluid not required tooperate the servomotor 53 is discharged through theportsAS: andand-thecheck valve back into the reservoir 38, an extremely rapid actionbeingobtained by-this arrangement. The servomotor bore 55 contains apiston. 55 mounted on a piston rod- 5'! extending through one end of Thepiston-56 is urged toward the right by a coil spring 58, the oppositeend of which is engaged by the end of an adjusting screw 50 which isthreaded through a bore 60 in one end ofthe servomotor cylinder 52.

The servomotor piston 5! is connected to the outer end of a valve rod 6|which isreciprocably mounted in a standard four-way control valve 62.The four-way control valve 62 is conventional and well-known amonghydraulic engineers, and its'detail s form no part of the presentinvention. A'ny suitable type of reversing valve may be used in place ofthefour-way valve 62 and a brief description of. its principal features,as shown in Figure 4, will suffl'ce. The three-headed hollow valve spool63 reciprocates in a valve bore 64 Figu-re 4) which is provided withspaced ports 'to which are connected a central pressure fluidsupply.pipe 65, pressure fluid service pipes 65 andGI on opposite sidesthereof, and a pressure' fluid discharge or exhaust pipe 68 connected tothe-cylinder bore 64 near the ends thereof so as to be covered by theend heads of the valve spool 63 when the valve is in its neutralposition. The pressure fluid supply pipe 65 is connected to a suitablehydraulic pump (not shown) and the pipe 68 leads to a fluid reservoir(not shown) from-which the pump draws its fluid. The control valve 62and servomotor 53 areboth mounted on a bracketfifl which is bolted. tothe underside of the feeding mechanism bed 70' (Figure 1) which in turnis bolted to the machine bed I5. The feeding mechanism bed 10' supportsthe feeding mechanism, generally designated II, by which the sheet stockor coil stock S is fed to the machine I 0.

Rising from the left-hand end of the bed I is an-upright I2 in the formof a metal block having a flat'top surface I3 over which the sheet stockS slides. The stock S is guided by grooved guide wheels 14 mounted onstuds I which are in turn threaded into slides 16 slidably mountedinT-shaoed grooves 11 so as to adapt the guide wheels I4 to varyingwidths of stock S. Set screws 18 serve to secure the slides E6 in the radjusted positions. The T-shaped grooves 11 are'formed in aforwardly-extending and overhanging.- p'ortionlS forming a part of theupright 12 The upright 12 and its surface 13 form the lower portion of astationary clamp generally designated which is intermittently operatedto alternately clamp and release the stock S in cooperation with amovable clamp BI of similar construction. The clamps 80 and 8| aredisclosed and claimed in my co-pending application Serial No. 734,904filed March 15, 1947 on which was granted the Haller patent No.2,467,740 issued April 19, 1949 for Step-by StepFeeding Device. and.their details form no part of the present invention.

The clamps 80 and 8I are of similar construction, hence a singledescription will be suflicient for both. Each clamp is provided with ablocklike' casing 82 having a port 83 into which is threaded a pipeconnection 84. The pipe connection 04 of the stationary clamp 80 isconnected to the service pipe 61, whereas the connection 84 of themovable clamp BI is connected by a flexible pipe 85 to the service pipe66. The movable clamp 8| has a block-like base 86 corresponding-to theblock-like upright 12 and having a similar flat surface 81 at the topthereof over which the stock S slides.

The port 83 opens into a downwardly-inclined passageway-88 (Figure 1)leading to a laterallyelongated chamber 89 closed by an elongated plate90 bolted to the casing 82. Leading downwardly from the chamber 89 areinclined multiple bores 9| containing reciprocable plunger pins 92(Figure 2). The plungers 92 are urged downward in the bores 9| by coilsprings 93, and their lower ends engage an elongated roller 94 which ismounted in a tapering recess 95 having an upper wall surface 96 inclineddownward toward the walls or surfaces 13 or 81 over which the stock Sslides. The clamps 80 and N are each provided with a slot 01 extendingtherethrough for the passage of the stock S (Figure 3). Bolts 98 extenddownward through the casing 82' to secure it to the upright 12 or base88 as the case maybe (Figure 1).

The upright 12' is provided with horizontallyspaced sockets 99 forreceiving'the forward ends of spaced parallel guide rods I00, therearward ends of which are mounted in bores IOI in arms I02 extendinglaterally outward from the cylinder I03 of the hydraulic feedingcylinder or motor I04. The motor I04 is of the variable stroke typedisclosed and claimed in my Patent No. 2,428,493 issued Oct. 7, 1947 forStock Feeding Mechanism for Punching, Stamping and Cutting Machines.

The cylinder I03 of the motor I04 has a cylinder bore I05 in whichreciprocates a compound adjustable stroke piston generally designatedI06. The latter consists of a hollow piston rod I01 (Figure l) the outerend of which is reduced in diameter and, after passing through a boreI08 in the clamp base 86, terminates in a threaded portion carrying anut I09. The inner end of. the piston rod I01 carries a head H0.

The piston rod I01 is provided with an internally-threaded bore III intowhich is threaded a threaded stem I I2 of a movable piston head I i 3,this, in turn, being bored longitudinally with a bore of squarecross-section adapted to slidably receive a square shaft H4 carrying ahand wheel H5 at its outer end and a similarly-bored collar I I 0located on the inner side of the cylinder head Ill. The opposite ends ofthe cylinder bore I05 are provided with ports H8 and IIS into which arethreaded branches of the service pipes 66 and 6! respectively. Thus, byrotating the hand wheel II5, the piston heads H0 and II 3 may be '5caused to move toward or away from one another, thereby lengthening orshortening the stroke of the compound piston I06 in the cylinder boreI05.

In order to guide the movable clamp 8| in its reciprocation, the basethereof is bored as at I20 (Figure 3) for the passage of the guide rods00. The rearward portion of the stock S is also guided by grooved guidewheels 14 similar to those previously described and similarly numberedand similarly mounted on studs 15 carried by slides 16 reciprocating inT-slots 11 formed in arm portions I2I extending laterally outward fromthe upper rearward end of the cylinder I02 (Figure 2).

To insure that the sheet or strip S of material will be grasped withsufficient pressure to prevent slippage before the feeding strokecommences, a sequence valve, generally designated I25 (Figures 1 and 6)is preferably inserted in each of the service pipes 66 and 61, alongwith a check valve I23. The sequence valve I25 consists of a casing I21having a longitudinal bore I28 terminating at one end in a plungerlifting bore I29 of reduced diameter having a passageway I30 extendingfrom the outer end thereof back to the intake port I 3! which leads intoan annular enlargement E32 from which the outlet port I33 leads outward.Both of these ports are connected to gaps in the service pipes 66 and 61so as to be in series therewith. The annular enlargement I32 forms apart of the lower end of the bore I28, which portion, for convenience,will be designated as the chamber I32.

Surrounding the bore I28 above the chamber I32 and spaced away from itis an annular enlargement I34 from which an auxiliary port or sequenceport I35 opens outward. Pipes I36 and I31 run from the sequence valvesI25 in the service pipes 66 and 61 respectively to the opposite endports H8 and III! of the hydraulic feeding motor I04 (Figure 2). Boltedto the upper end of the bore I28 is a cap I38 having a smaller threadedbore I39 extending longitudi nally thereof co-axial with the bore I28.Threaded into the bore I39 is an adjusting screw I40 having a socket MIin the lower end thereof adapted to receive the upper end of a coilspring I42, the lower end of which engages the upper end of a valveplunger I43 and urges it downward. A lock nut I44 locks the screw I40 inits adjusted position for regulating the force exerted by the coilspring I42 upon the valve plunger I43 whereas a cap I45 with a socketI46 therein covers the otherwise exposed end I41 of the screw I40.

The valve plunger I43 is of approximately cylindrical form with headsI48 and I49 separated from one another by a reduced diameter neck I50lying within the chamber I32. The lower end of the valve plunger I43 isengaged by a plunger-lifting piston I5I which is reciprocable in theplunger-lifting bore I29.

In the operation of the clamping arrangement shown in Figures 1 to 4inclusive, the sheet or coil stock S is threaded through the slots 91 inthe movable and stationary clamps 8| and 80 as shown in Figure 1, andthe hand wheel II5 rotated to adjust the stroke of the hydraulic motorI04 to the desired feeding stroke for the stock S, depending upon thesize of workpiece to be stamped or punched out by the punch unit 2 I.The operator then starts the hydraulic pump (not shown) which supplieshydraulic pressure fluid through the supply pipe 65 to the four-way con-6 trol valve 62, which in turn actuates the fixed and movable clamps and8I alternately as well as actuating the hydraulic motor I04 to advancethe stock S.

The operator now starts the machine I0 causing the platen I4 to descendand punch out a workpiece from the stock S. As the platen I4 rises, itcarries the cam plate 25 upward, causing the inclined portion 30 of thecam groove 28 to engage the roller 32 on the end of the piston rod 34and shift the piston 49 to the right. Assuming the cylinder bore 41 tobe full of fluid, this fluid is forced under pressure through the pipe54 into the right-hand end of the cylinder bore 55 of the servo-motor53, shifting its piston 56 and piston rod 51, as well as the valve rodSI of the four-way control valve 62 to the left, compressing the coilspring 58. When the valve rod 6| and three-headed spool 63 are thusshifted to the left to the opposite position from that shown in Figure4, pressure fluid from the supply pipe 55 can pass directly into theservice pipe 68, since the middle head of the valve spool 53 is now tothe left of the supply pipe 85.

The pressure fluid passing through the pipe 66 enters the annularenlargement or chamber I32 through the inlet port I3I and passes outwardthrough the outlet port I 33 into the remainder of the pipe 89 andthence through the flexible pipe into the clamp chamber 89 of themovable clamp BI. There it acts against the upper ends of the plungers92, forcing them downward and causing the roller 94 to be wedged tightlyinto the converging chamber 95. This causes the roller 04 to reactagainst the inclined surface 98 so as to force the stock S tightly intofrictional engagement with the surface 81 of the base 86 of the movableclamp 8 I.

Meanwhile, a portion of the pressure fluid in the service pipe 56 haspassed through the passageway I30 (Figure 6) of the first (right hand)sequence valve I 25 (Figure 2) into the lower end of the plunger-liftingbore 529 where it acts against the lower end of the piston I5I. When thepressure has risen to a point where the force exerted on the piston i5iis able to overcome the force of the coil spring I42, it shifts thevalve plunger I43 upward, causing the head I49 to pass above the annularenlargement or chamber I34 so that the space around the neck I50interconnects the annular enlargements or chambers I32 and I34. Pressurefluid then flows from the chamber I32 through this spaced and outwardthrough the auxiliary port I35, thence through the pipe line I33 to theport H8. The pressure thus entering the right-hand end of the cylinderbore 505 of the feeding motor I04, acts against the compound piston headH3 and shifts it, the piston rod I01 and the movable clamp BI to theleft, shifting the stock S to the left.

The clamp BI continues to move the stock S a distance equal to thelength of stroke of the compound piston I06, whereupon it halts.Throughout all of this feeding movement, of course, the stationary clamp80 has been in its released position because the service pipe 51 leadingthereto has been connected through the second sequence valve I25 andthrough the control valve 52 to the exhaust pipe 68. Thus, there is nopressure at this time in the chamber 89 of the stationary clamp 80,hence the roller 94 thereof fails to tightly grip the stock S as itslides past, propelled by the moving clamp 81. At the same time, thefluid displaced from the left-hand end of the, motor cylinder Hi3escapes through the pipe I31 and check valve E26 into the service pipe6'! and thence, in the manner stated above, to the exhaust pipe 58.

When the platen l4 reaches the top of its stroke and starts downwardupon a punching stroke, the foregoing motions are reversed. The downwardtravel of the platen l4 causes the cam groove of the cam plate 25 tomove the piston rod 34 of the motive device 35 to its left-hand positionas shown in Figure 1. This, in turn, creates a suction in the pipe 54and right-hand end of the servo-motor cylinder bore 55, permitting thecoil spring 58 to shift the servo-motor piston rod El, valve rod ti andvalve spool 53 of the control valve 82 to the right into the positionshown in Figures 1 and 4. This reverses the flow of the pressure fiuidin the supply pipe (35 from the service pipe 5 to the service pipe 3?.

This action actuates the clamp to cause its roller 94 to tightly gripthe stool: S and hold it stationary against the surface it on theupright 12. When the pressure within the chamber 89 of the fixed clamp8i! rises to an amount sufficient for the piston Edi to overcome theforce of the coil spring M2 and lift the plunger i i-S thereof, in thesecond sequence valve 525 located in the service pipe pressur fluid isthen enabled to flow from the pipe through the bore 28 to theenlargement lite and out through the auxiliary port Hi5 and pipe #3? tothe port H9 at the left-hand Cl" the cylinder I03 of the hydraulic motor1%. Thus, the fixed clamp 851 securely grips the stool: S before thehydraulic motor 5 becomes operativc to retract the movable clamp Ellback to its starting point. When pressure fluid from the branch 13? ofthe pipe 6? enters the port HS the left-hand end of the cylinder bore ofthe feeding motor lot, it retracts the compound piston l 6% and themovable clamp 85 to the right into the positions shown in Figure 1.Since the service pipe 65 is now connected to the discharge or exhaustline '58, no pressure exists in the chamber 85 of the movable clamp 8!,hence the roller 9 thereof releases its grip on the stock. S nowtemporarily held by the stationary clamp 89 and permits it to slidethereof while the movable clamp 8! is being retracted. Meanwhile, thefluid displaced from the right-hand end of the cylinder 33 of thehydraulic motor lu l escapes through the port HE, auxiliary line Hi8 andcheck valve I26 into the service pipe now connected to the exhaust pipe68, as stated above. The platen I l continues its downward. stroke andthe punch unit 2! punches out another workpiece, after which the plateni4 moves upward and the foregoing cycle of operations is repeated.

As previously stated, the cylinder bore 3? of the motive device 35 is ofconsiderably larger capacity than the servo-motor cylinder boreAccordingly, during the first part of the stroke of the piston head t9,the servo-motor cylinder bore 55 is rapidly filled as its piston headmoves to the left. The excess fluid in the cyl nder bore a? is thendischarged through the port 66, lifting the ball check valve or reliefvalve 42 against the thrust of the coil spring and causing the excessfluid to escape through the port into the reservoir 33.

The modification shown in Figure 5 is similar to the correspondingportion shown in the upper left-hand corner of Figure 1, except that thedirection of the cam groove 28 is reversed in the cam plate 25. Themotive device 35 remains exactly the same. In the operation of themodi-. fication shown in Figure 5, however, the motive piston 39 movesto the left on the upstroke of the platen M and to the right on thedownstroke thereof, exactly the reverse of the motion in Figures 1 to 4inclusive. The remainder of the circuit and mechanism of Figure 5 arethe same, except that the stock S is advanced on the downstroke of theplaten l4 and held stationary on the upstroke thereof. It is, of course,obvious that all motion of the stock S should cease before the punchesI9 and 20 reach it.

What I claim is:

1. An intermittent feeding arrangement for feeding sheet material to apress having a 'reciprocable material-processing member, saidarrangement comprising a stationary material support, a movable materialsupport, a pressure-fluid-actuated clamp mounted adjacent each supportand having a clamping member movable hydraulically into clampingengagement with said material against its respective support, ahydraulic motor operatively connected to said movable support to movethe same, a pressure-fluid distributor hydraulically connected to saidclamps and to said hydraulic motor, a servo-motor operatively connectedto said pressure fluid distributor to shaft the same, a pressure-fluidpump hydraulically connected to said servo-motor and mechanismoperatively connecting said material processing member to said pumpwhereby the motion of said materialprocessing member shifts saidservo-motor to responsively shift said distributor and, supply pressurefluid alternately to said clamps and to the opposite sides of saidmotor.

2. An intermittent feeding arrangement for feeding sheet material to apress having a reciprocable material-processing member, said arrangementcomprising a stationary material support, a movable material support, apressure-fluid-actuated clamp mounted adjacent each support and having aclamping member movable hydraulically into clamping engagement with saidmaterial against its respective sup port, a hydraulic motor operativelyconnected to said movable support to move the same, a pressure-fluiddistributor hydraulically connected to said clamps and to said hydraulicmotor, a cam device operatively connected to said material-processingmember, a sermo-motor operatively connected to said pressure fluiddistributor to shift the same, and a pressure fluid pump hydraulicallyconnected to said servomotor and operatively engageable with said camdevice whereby the motion of said materialprocessing member shifts saidservo-motor ;to responsively shift said distributor and supply pressurefluid alternately to said clamps and to the opposite sides of saidmotor.

3. An intermittent feeding arrangement for feeding sheet material to apress having a reciprocable material-processing member, said arrangementcomprising a stationary material support, a movable material support, apressure-fluid-actuated clamp mounted adjacent each support and having aclamping member movable hydraulically into clamping engagement with saidmaterial against its respective support, a hydraulic motor having acylinder and a reciprocable piston therein operatively connected to saidmovable support to m th same, a pressure-fluid distributor hydraulicallyconnected to said clamps and to said hydraulic motor, saidpressure-fluid distributor having a pair or" alternatively selectiveservice ports either of which becomes a pressure-fluid delivery portwhile the other service port becomes a fluid return port, a servo-motoroperatively connected to said pressure-fluid distributor to shift thesame, a pressure-fluid pump hydraulically connected to said servo-notor,mechanism operatively connecting said material processing member to saidpump whereby the motion of said material-processing member shiftssaid'distributor to supply pressure fluid alternately to said clamps andto the opposite ends of said cylinder, one of said service ports beinghydraulically connected to one end of said cylinder and to one of saidclamps and the other service port being hydraulically connected to theother end of said cylinder and to the other of said clamps.

4. An intermittent feeding arrangement for feeding sheet material to apress having a reciprocable material-processing member, said arrangementcomprising a stationary material support, a movable material support, apres sure-fluid-actuated clamp mounted adjacent each support and havinga clamping member movable hydraulically into clamping engagement withsaid material against its respective support, a hydraulic motor having acylinder and a reciprocable piston therein operatively connected to saidmovable support to move the same, a pressure-fluid distributorhydraulically connected to said clamps and to said hydraulic motor, aservo-motor operatively connected to said pressure fluid distributor toshift the same, a pressure fluid pump hydraulically connected to saidsermo-motor and mechanism operatively connecting said materialprocessing member to said pump whereby the motion of saidmaterial-processing member shifts said servo-motor to responsively shiftsaid distributor and supply pressure fluid alternately to said clampsand to the opposite ends of said cylinder.

5. An intermittent feeding arrangement for feeding sheet material to apress having a reciprocable material-processing member, said arrangementcomprising a stationary material support, a movable material support, apressure-fluid-actuated clamp mounted adjacent each support and having aclamping member movable hydraulically into clamping engagement with saidmaterial against its respective support, a hydraulic motor operativelyconnected .to said movable support to move the same, a pressure-fluiddistributor hydraulically connected to said clamps and to said hydraulicmotor, said pressure-fluid distributor having a pair of alternativelyselective service ports either of which becomes a pressure-fluiddelivery port while the other service port becomes a fluid return port,a servomotor operatively connected to said pressure-fluid distributor toshift the same, a pressure-fluid pump hydraulically connected to saidservomotor, mechanism operatively connecting said material processingmember to said pump whereby the motion of said material-processingmember shifts said distributor to supply pressure fluid alternately tosaid clamps and to the opposite sides of said motor, one of said serviceports being hydraulically connected to one side of said motor and to oneof said clamps and the other service port being hydraulically connectedto the other side of said motor to the other clamp, and a sequence valveconnected between each clamp and its respective side of said motor andhaving a yieldingly-urged valve member therein shiftable in response toa predetermined rise in pressure in said clamp to divert pressure fluidto said motor whereby to exert a predetermined clamping grip on saidmaterial before permitting said motor to shift said material.

JOHN HALLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,096,073 Spencer Oct. 19, 19372,166,428 Clark July 18, 1939 2,301,028 Esch Nov. 3, 1942 2,347,261Harrington et al. Apr. 25, 1944 2,354,860 Hartsock et al. Aug. 1, 19442,367,248 Vickers et al Jan. 16, 1945 2,379,002 Haller June 26, 19452,406,508 Papsdorf Aug. 27, 1946 2,409,968 Welsch Oct. 22, 19462,428,493 Haller Oct. 7, 1947 2,467,740 Haller Apr. 19, 1949 2,470,252Kyle May 17, 1949

